Digital camera's shutter lag: Why are SLR faster?

Discussion in 'Digital Cameras' started by Antoine Garric, Apr 12, 2005.

  1. By reading the press and searching into this forum history I got a fact:
    SLR systems are faster: meaning they have shorter shutter lag.

    So far I have had a few camera the latest being a coolpix SQ, the
    shutter lag is so long that I am considering investing into an SLR
    camera Nikon 70 or Canon 350 for example. (I am talking about the lag
    with pre-focus)

    What I don't understand is why SLR are faster? in fact they need to move
    the mirror/prism so they should be even slower.

    Is it just the price or is there a technical reason because of which you
    cannot have a faster sensor when you also use it to visualize the image
    in real time. Is there a time to reconfigure the sensor from the
    vizualisation mode to the shooting mode?

    I don't want an SLR, I would preffer a bridge (smaller, 10x zoom is fine
    with me I don't need to change lenses, most of the time I prefer the
    screen rather than the viewfinder - By the way my SQ have no viewfinder).

    If some vendor could build a bridge with a good latency I would buy it
    immediatly even at the price of a SLR.

    Do I have a chance to see a bridge with good latency any time soon?

    By the way do you know a good site or magazine with a comparison of
    shutter lag.

    Thanks for your advise.
    Antoine Garric, Apr 12, 2005
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  2. a écrit :
    Thanks for your swift answer. I looked at this site and did not find
    mention of latency/lag for example I browsed the 2o page review of the
    Canon 350D and didn't find it. Any specific page to look at?

    Antoine Garric, Apr 12, 2005
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  3. Paul Rubin wrote:
    The Nikon 8400 has both a focus sensor and can use CCD focus if needs be.
    This combination makes it fast in use.

    David J Taylor, Apr 12, 2005
  4. I believe it's an IR sensor, although the specifications in the manual say
    "AF sensor" and even DP Review just says "external sensor". Behind the
    glass plate on the camera there look to be two further lenses:

    above the gold "8.0 megapixels ED" logo.

    David J Taylor, Apr 12, 2005
  5. There are two factors at work: autofocus and LCD preview.

    DSLRs use phase-measuring autofocus systems that have extra optics and
    CCDs that are optimized for focus only. This makes them fast at
    focusing. From a single measurement, the camera knows which direction
    and approximately how far to move the focus motor, even before the motor
    starts moving.

    Most P&S digicams use a simple contrast-measuring autofocus system that
    requires them to repeatedly read images from the sensor while
    (relatively) slowly moving the lens through a range of focus positions.
    This is cheap (no extra hardware), but slow. A few P&S cameras have
    external autofocus systems like P&S film cameras, so they can be faster.

    In addition, it takes a bit of time to reconfigure the camera from "live
    preview" to "picture taking" mode. The shutter is open during preview,
    so it has to close. Then the CCD is cleared (by reading it out
    rapidly). Only then can the shutter open and close for the actual
    exposure. In comparison, in a DSLR the sensor is normally in the dark
    and can be kept cleared. When you want to shoot, the mirror flipping up
    is the only delay.

    Some P&S digicams can be made to operate noticeably faster by (a)
    switching to manual focus so there's no autofocus delay and (b) turning
    off the LCD preview, which allows the shutter to remain closed.

    Dave Martindale, Apr 12, 2005
  6. Antoine Garric

    Ron Hunter Guest

    You might check the specs on the Kodak DX7590. It, and similar cameras,
    have shutter lag figures only slightly slower than DSLRs.
    Ron Hunter, Apr 12, 2005
  7. Very good explaination! I have been asking this question to so many
    people recently and no one could give me any reasonable answer.

    Do you have a refernece to a book or site explaining this?

    Thanks agains,

    Dave Martindale a écrit :
    Antoine Garric, Apr 12, 2005
  8. Antoine Garric

    larrylook Guest

    I've heard it said that dSLR can be more likely to get auto WB wrong than
    P&S because it sets WB on the basis of small sensor and quickly, so less
    info on which to select best WB.
    larrylook, Apr 13, 2005
  9. It doesn't get any more essential than Dave's reaction. Try to Google
    on the Groups, it may turn up more references to similar (less
    condensed) info.

    Bart van der Wolf, Apr 13, 2005
  10. Antoine Garric

    Ron Hunter Guest

    One problem I see with it is that so far it seems to be vaporware. At
    least in the US.
    Ron Hunter, Apr 13, 2005
  11. Antoine Garric

    Gnekker Guest

    Thanks for your swift answer. I looked at this site and did not find
    Usualy on page 4 on reviews for P&S cameras there is a detailed analysis of
    all timing and delays. Also new models of P&S cameras are much faster now
    (for example, my Fuji F810 feels really snappy in action).
    Gnekker, Apr 13, 2005
  12. Antoine Garric

    Tony M Guest

    For some reason Ricoh don't seem to deal in the US
    don't know why, they make good cameras (digital and film)

    Tony M
    Tony M, Apr 13, 2005
  13. Antoine Garric

    Diane Wilson Guest

    I would rarely use auto white balance anyway, since the "balance"
    is affected by the dominant colors in the photograph. As far as
    I'm concerned, auto white balance is a P&S feature that doesn't
    belong on a serious camera.

    Much better to set your white balance for the type of light you're
    shooting in, and go with it. Film photographers got by just fine
    for years with nothing but daylight and tungsten film, and it worked
    just fine. It's nice to have additional white balance choices for
    flourescent and for open shade, but "auto" is not a useful choice.

    Diane Wilson, Apr 14, 2005
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